The majority of carpets or upholstery goods are made by tufting or weaving yarn into a primary backing, such as a woven or nonwoven textile base. The pile loops or tufts are not securely fastened in the tufting or weaving process and can be easily pulled from the primary backing. Necessary anchorage is provided by applying a free flowing adhesive material to the backside of the carpet. This anchorage is commonly referred to as tuft lock. Another important physical property of carpet is dimensional stability. Carpets or upholstery goods having good dimensional stability do not tend to creep and buckle under normal use. Currently, the carpet industry achieves dimensional stability with the use of a secondary backing. Common secondary backings being used in the industry include both natural and synthetic woven or non-woven fabrics. Jute is a common example of a natural woven secondary backing. Synthetic secondary backings are typically made from polypropylene and can be either woven or non-woven. The backings are laminated to the backside of the carpet with latex based adhesives. Carpets and upholstery goods having a secondary backing are used principally on residential carpeting. Without this additional secondary backing material applied to the adhesive material on the backside of the carpet, the carpet is said to have a unitary backing. Carpets having a unitary backing are used principally in commercial applications. The majority of commercial carpeting is installed directly on the floor using water based adhesives. The basic requirements for commercial carpeting are that they have good tuft lock and can be easily installed with water based latex adhesives. The major problems associated with installation is a curling phenomenon occurring at the peripheral edges of the carpet known as edge curl. Tuft lock performance and edge curl are interrelated. Commercial carpeting backed with urethane compositions and possessing good tuft lock normally has severe edge curl problems. Likewise, carpeting having acceptable edge curling properties is deficient in tuft lock. Commercial carpeting exhibiting severe edge curl must be installed with expensive adhesives.
The current polyurethane unitary carpet backing systems known in the art all possess good dimensional stability, bundle wrap and pilling and fuzzing characteristics. However, they do not possess adequate tuft lock performance with acceptable edge curl characteristics.
The present invention not only provides carpeting with good dimensional stability, bundle wrap and pilling and fuzzing characteristics but adequate and often much improved tuft lock performance with acceptable edge curling properties. Adequate tuft lock performance is characterized by having a force greater than about 12 pounds (5.44 kilograms) necessary to pull one tuft out of the carpet. Acceptable edge curl performance is characterized by a curl of not greater than about 4.1 centimeters.